We propose to continue investigations into the mechanisms of DNA transport and recombination which occurs during genetic transformation in Bacillus subtilis. We will attempt to identify enzymatic activities involved in these properties. In particular, we will investigate the roles of various deoxyribonucleases and DNA polymerases. We will explore the fate of the recipient replicon during transformation, investigating the appearance of discontinuities in the recipient DNA strands and changes in the folded chromosome structure. We will investigate the structure of joint molecules formed during transformation and the processes which discriminate against nonhomologous DNA base sequences. We will develop a novel plasmid system to aid in these studies, using techniques of cloning bacterial DNA fragments on plasmid vectors. Finally, we will attempt to develop a system for the study of genetic recombination in vitro.